Interaction Object Graphs: An Executable Graphical Notation For Specifying User Interfaces

Interaction Object Graphs(IOGs) are a graphical specification method based on an extended state machine. Their goal is to provide an understandable representation of man-machine dialogues. (Wasserman 85) used finite state machines to specify dialogues. However, state diagrams have severe problems when used to specify more complex dialogues. The number of states and transitions required grows uncontrollably as common interaction techniques such as modal dialogue boxes are introduced. Direct manipulation interfaces also introduce the possibility that the user will interleave tasks. While easily modelled by parallel processes, task interleaving is very difficult to describe with a finite state machine. Some form of extended state machine is required to handle direct manipulation interfaces. A number of methods have been tried. (Jacob 86) used an extended state machine which grouped states into meta-states and allowed transitions from a meta-state. Parallelism was handled implicitly by the execution environment. (Wellner 89) adapted Harel’s Statecharts (Harel 88) for use in dialogue specification. Statecharts include explicit parallelism and a history-based meta-state restart. (Palanque & Bastide 94) used Petri nets as their extended state machine.Godkänd; 1998; 20061201 (ysko)